Tweak license wording

- Add back source code link
- Shorten "Licensed under..." wording
- Remove link to CC license on homepage

_layouts/lecture.html

@@ -18,5 +18,5 @@ <h1 class="title">{{ page.title }}{% if page.subtitle %} <span class="subtitle">
 
 <div class="small center">
 <p><a href="https://github.com/missing-semester/missing-semester/blob/master/{{ page.path }}">Edit this page</a>.</p>
-<p>This content is licensed under <a href="https://creativecommons.org/licenses/by-nc-sa/4.0">CC BY-NC-SA</a>.</p>
+<p>Licensed under <a href="https://creativecommons.org/licenses/by-nc-sa/4.0">CC BY-NC-SA</a>.</p>
 </div>

index.md

@@ -78,6 +78,7 @@ AeroAstro](https://aeroastro.mit.edu/) for A/V equipment; and Brandi Adams and
 ---
 
 <div class="small center">
-<p>This content is licensed under <a href="https://creativecommons.org/licenses/by-nc-sa/4.0">CC BY-NC-SA</a>.</p>
+<p><a href="https://github.com/missing-semester/missing-semester">Source code</a>.</p>
+<p>Licensed under CC BY-NC-SA.</p>
 <p>See <a href="/license">here</a> for contribution &amp; translation guidelines.</p>
 </div>